The general class of polymers of carbon monoxide and one or more ethylenically unsaturated hydrocarbons has been known for some years. Brukaker, U.S. Pat. No. 2,495,285, produced such polymers of relatively low carbon monoxide content in the presence of free radical catalysts such as benzoyl peroxide. British Pat. 1,081,304 produced such polymers of higher carbon monoxide content in the presence of alkylphosphone complexes of palladium as catalyst. Nozaki extended the process to arylphosphone complexes of palladium; see, for example, U.S. Pat. No. 3,694,412, also see U.S. Pat. No. 3,914,391.
More recently, the class of linear alternating polymers of carbon monoxide and unsaturated hydrocarbons, now known as polyketones, has become of greater interest, in part because of improved methods of production. Such methods are shown by European Patent Applications 0,181,014 and 0,121,965. The disclosed processes employ, inter alia, a compound of a Group VIII metal such as palladium, an anion of a non-hydrohalogenic acid having a pKa below 2 and a bidenatate ligand of phosphorus. The resulting polymers are generally high molecular weight thermoplastic polymers having utility in the production of articles such as containers for food and drink.
There are a variety of methods for preparing polyketones, copolymers of an olefinically unsaturated compound and carbon monoxide. U.S. Pat. No. 3,689,460 and 3,694,412 disclose two processes for preparing polyketones. The catalysts described therein are complexes of a palladium, chloride or allyl palladium chloride and two trihydrocarbyl phosphine monodentate-like ligands, such as triphenylphosphine. However, in these disclosed processes the polymer yields are relatively small, less than 35 grams per gram palladium per hour at a pressure of 70 bar. A need has existed to devise a process with a higher yield.
Another process for preparing polyketones is discussed by Sen and Li in an article entitled "Novel Palladium (II)-Catalyzed Copolymerization of Carbon Monoxide With Olefins", J. Am. Chem. Soc. 1982, 104, 3520-3522. This process generates higher yield than the other disclosed processes.
The process for preparing polyketones disclosed in European Patent Application No. 0121965 is directed towards a preparation of polyketones to obtain a high yield, by polymerizing a mixture of carbon monoxide and alkenically unsaturated hydrocarbon in the presence of a Group VIII metal catalyst containing ligands, wherein hydrocarbon groups are bonded to an element from Group Va, characterized in that, as catalyst, a complex compound is used that is obtained by reacting a palladium, cobalt or nickel compound, a bidentate ligand of the general formula: EQU R.sub.1 R.sub.2 --M--R--M--R.sub.3 R.sub.4,
in which M represents phosphorous, arsenic or antimony, R.sub.1, R.sub.2, R.sub.3, and R.sub.4 are identical or different hydrocarbon group, and R represents a divalent organic bridging group having at least two carbon atoms in the bridge, none of these carbon atoms carrying substituents that may cause stearic hindrance, and an anion of an acid with a pKa of less than two, provided the acid is neither a hydrohalogenic acid nor a carboxylic acid.
Polyketones prepared by the above-described novel high yield process can be treated wit one or more of a variety of solvents to produce solution cast films with barrier properties relative to the transmission of oxygen and carbon dioxide.